Potions come in four forms: they may be a liquid, salve, oil or infusion. This information is found at the top of the reverse side of the card that accompanies the potion.

A liquid is an elixir or philtre that is drunk.
A salve is a balm or ointment that is smeared on the skin,or into a wound.
An oil is a thick viscous liquid that is daubed or poured onto a weapon.
An infusion is a volatile substance that reacts to heat. Infusions are burnt or boiled and the steam or smoke they produce inhaled.

I think for most salves it makes sense to start with some simple skin cream.
For this one, maybe add some blue food-colouring and maybe a bit of sawdust? Or put it in a blender with some grass?

[quote] Bloodharrow Philtre
Form: Liquid.
Form: This translucent red liquid has tiny white particles suspended in it. It has a spicy scent, and a tiny amount on your tongue or your finger tingles unpleasantly for a moment. [/quote]

For the translucency, perhaps cloudy ginger-beer. That also has a bit of spiciness. Add some red colouring. Maybe a bit of powdered chalk?

[quote]
Elixir Vitae
Form: Liquid.
Description: This translucent liquid is tinted a pale blue-green. It has a clean, fresh scent. A tiny drop of the sticky fluid on your tongue or your finger tingles pleasantly for a moment. [/quote]

Getting that combination of smell and taste is quite a challenge. I think smell is more important if it has to be one or the other.
For the translucency, perhaps a little pectin or arrowroot or cornflour? Any of those will also thicken it.

[quote] Vernal Balm
Form: Salve.
Description: This blood-red ointment smells delicious. It has an oily, greasy texture if you rub it between finger and thumb, and it is quickly absorbed into your skin causing your entire hand to tingle. [/quote]

So, a light skin cream/lotion with some red colouring. Might be nice if it didn’t stain though. How to achieve that?
As for the smell, perhaps a drop of essential-oil of orange mixed in.

[quote] Suffusion of Blood
Form: Liquid.
Description: When this blood-red elixir catches the light, it glows with a faintly translucent aura. The scent smells of freshly cut grass, and causes your nostrils to tingle. The sweet, fruity taste causes a moment of dizziness. [/quote]

Another one that calls for a cut-grass scent. I don’t know how to give something a fruity taste without a fruity smell. Any ideas?
Redness and translucency: see above.

[quote] Decoction of the Hungry Moon
This black liquid has an unpleasantly oily texture, and often contains small amounts of bladeroot or marrowort matter as sediment that settles on the bottom of a flask. It must be shaken thoroughly before consuming. It tastes very unpleasant indeed, and while some apothecaries add sugar to the mixture the general consensus agrees that doing so can damage the potion’s effectiveness.
Form: Liquid.
Description: This black, oily elixir has a thick sediment at the bottom that seems to drink in any light that hits it. It tastes vile, like rotting meat. It would require quite an effort of will for most people to drink this liquid. [/quote]

Perhaps a little finely ground charcoal for the sediment.
I remember Isca posting something about rotting-meat smell in another thread…

[quote] The Barren Watchtower
This gritty black elixir contains tiny pale particles in suspension, and has a dehydrating effect on the drinker.
Form: Liquid.
Description: This black, oily elixir seems to drink in any light that hits it. The thick sediment at the bottom hangs in the liquid for several minutes after it is shaken up. The salty, bitter taste gives you an urge to rinse your mouth out. [/quote]

Something with salmiaki in it? And Angostura bitters if you’re willing to include alcohol? Maybe chalk for the pale bits.

[quote] Magpie Infusion

This volatile oil dissolves quickly in warm water, or can be thrown directly onto hot coals or open flame to create a small cloud of strongly scented steam.
Form: Infusion.
Description: This oily blue substance smells of summer flowers. When exposed to the air, it begins to evaporate. A tiny amount on your fingertip immediately begins to bubble and soon evaporates into a thin blue-tinted cloud. [/quote]

Lavender essential oil, with a little blue colouring in it.

[quote] Ravenwing Infusion

This pale red concoction produces a thick, lingering steam that hangs in the air for several moments unless actively inhaled.
Form: Infusion.
Description: This crumbly red substance smells strongly of exotic spices. When rubbed between finger and thumb the spicy scent intensifies dramatically.[/quote]

Powdered cinnamon and allspice, bound together with a tiny bit of sandalwood oil or maybe just by being wetted with water, compressed and allowed to dry.

[quote] Goosewhisper Infusion
This midnight blue liquid hisses and bubbles when exposed to heat, and releases a cloud of shimmering barely visible steam. If it is inhaled deeply, a chill sensation emanates from the chest through the whole body.
Form: Infusion.
Description: This midnight blue solution is a thick, resinous liquid. It has a sweet, sharp scent that causes your nostrils to tingle and chills your lungs. The unpleasant, acrid flavour makes drinking it unappealing. [/quote]

I’ll leave it there for the time being, but Goosewhisper Infusion still wants addressing, along with the recipes from
Lambent Essences
Legacy of Thorns
Magnum Opus
Master Medicinal
Philtres of the High Peaks
Philtres of War
The Assassin’s Gate
The Winter Moon
Tisanes of the Labyrinth
Tonics of the Deep Forest
Tonics of the Open Sky
Tonics of True Eminence

I’m not a potion maker but one from our group recommends the following:

"Bloodharrow philtre: red aftershock with hundreds & thousands. Will taste alcoholic and burn a little. Hundreds & thousands will bleach to give white flecks and the residue of their dye will make it a little cloudy.

Goosewhisper: I’ve used lemon and teatree oils with some blue food dye and a drop of water in an oil burner. Not really viscous enough but otherwise looks and smells the part."

just wondering if this is 100% necessary as a new player would some simpler physrep be appropriate

No, I was just trying to work out how to do it really well.
I reckon a perfectly reasonable minimum could be an empty non-transparent little pot or jar (for a salve) or bottle (for a liquid or powder), and just roleplay using the stuff.

That also means they won’t go off or spill. Having mouldy potion gunk or decomposed cork all over your kit is not nice. I used alcohol in my physick physreps as a preservative (My vervain physrep was tea leaves in cheap vodka). I’d tend towards spirit based, syrup-based or not actually a liquid.

As you’re factoring smell and taste are you actually expecting people to consume the potions?? Plenty of people have allergies and I wouldn’t want to waste precious time cross referencing my physrep ingredients list in game! I had assumed the actual consumption was roleplayed and it would be sufficient to have a substance that matched the physical description in a sealed bottle? However if the taste and smell factor is purely for your own sense of authenticity, I get that

I’m in the middle of making some new physreps and had planned on not making the consumables (drink/smoke) actually consumable because once I’ve handed the bottle over it may change hands several times and I can no longer check whoever is using it for allergies or warn about potential contamination or going “off” between events. Bottles of liquid will be capped with a suitable IC looking wax seal under which will be a glued-down screw-cap and a label saying “OOC: PHYSREP ONLY, DO NOT DRINK!”. Salves will be cold cream + stage makeup to pigment them to the right colour. The scents and flavours I’ll keep for when I’m IC compounding the brew and can make sure nobody’s going to be adversely affected in a suitably portentious IC way

Of course the points about safety and ingredient-checking are valid, but it’s only a minority of alchemical preparations that are meant to be drunk anyway.
Also it’s only a minority that will be needed in a big hurry.

I’d just like to share some things that worked, in case anyone else needs some. I didn’t make drinkable potions, but as a herbalist, I was carrying around stuff for the herbs.

Cerelean Mazzarine, which tended to be rubbed on. I used Boots cucumber moisturising cream. Looks pale green, smells floral, and is safe to rub on people (also useful vs sunburn). In a little wooden tub.
Bladeroot: A tiny (10ml) corked bottle, containing finely chopped ginger in brandy.
Marrowort: A similar bottle, containing a small amount of lemonade, with a drop of blue food colouring.
Imperial Roseweald: A small tight-woven cloth pouch, containing crushed pink peppercorns, tuermeric and chilie flakes. It’s a purgative, so while IC I’d toss a pinch down someones throat, OOC I’d ask if they want a sniff, to produce the IC tears, sweating, coughing and spluttering.
True Vervain. A 35cl brandy bottle: the tough plastic ones that look like glass, shaped like a hip flask. Containing lemonade with a shot of lemon juice and a few drops of food colouring. This is the one that got drunk on a regular basis, as a quick shot of water and sugar on the battlefield was was welcomed. I took along a litre of this mixed up, and topped up the flask daily.